As suspension load increases, the wheel travels into the vehicle in an upward arc. Too much travel (from too soft suspension) results in vastly different wheel camber depending on suspension load.

Most vehicles come from the factory with fairly soft springs made to deal with rough public roads. On the track, however, the range of lumpy road surfaces is much narrower. The generally smoother track surfaces make suspension stiffening a very helpful adjustment in the corners. However, like all things in tuning, too much of anything will negatively impact your lap times.

Stiffer suspension will better control suspension travel and the always-changing nature of your wheel camber. By holding wheel camber more constant, you can effectively keep the tires flat against the pavement for improved grip. Too much suspension travel will cause the camber angle to change—since suspension does not travel straight upward, but rather in an arc—which will result in vastly different levels of grip depending on the weight balance of the vehicle at any given moment.

Though as we mentioned, too much suspension stiffness can be a bad thing. Too-stiff suspension will not have the travel necessary to properly deal with imperfections in the road surface. Slight bumps in the road will then cause the tires to skip and lose traction. As such, stiffening the front suspension too much can cause understeer, while stiffening the rear suspension too much can cause oversteer. Conversely, you can reduce understeer and oversteer by softening the front and rear suspension, respectively.

Ride Height

Ride height is another adjustment you can make to the suspension. Generally, you want as low a ride height as possible without bottoming out the suspension on rough roads and under heavy weight transfer. However, balancing the front and rear ride height can let you play with your vehicle's center of gravity. A higher ride height in the rear will shift the car's center of gravity forward, which may help front tire grip.

Damping

While spring stiffness determines how much travel is in the suspension, dampers, also known as shocks, control the rate at which a vehicle's springs oscillate. Picture hitting a large bump at high speed in a standard road-going vehicle. After the bump, the car's suspension will continue to oscillate, bouncing up and down as the springs settle back down to their normal state. While this oscillation is good for driver comfort on public roads, it's not so desirable on the race track. The fluctuating weight balance during such oscillation can make tire grip unsteady, fluctuating with the suspension travel.

Stiffer shocks will control the oscillation of the suspension for a steadier weight balance. As well, stiffer springs will increase the speed of weight transfer, letting you more quickly and predictably redistribute the weight of the car with acceleration and braking. However, too-stiff shocks can overpower the springs, reducing their effectiveness at dealing with imperfections in the road and contributing to a loss of traction on uneven road surfaces, including bumps, dips and rumble strips.

Aero

Aerodynamic downforce acts as added weight, pushing down on either end of the vehicle to enhance the traction of the tires. Note that the effect of downforce increases with speed, and at low speeds downforce has little if any effect. Add downforce to the front of the car and you'll effectively give the front tires some added traction at speed. Add downforce to the rear of the car and you'll boost the grip of the rear tires at speed.

However, the benefits of downforce come at a cost. As we said, downforce effectively adds weight to the vehicle, which limits top-end speed and acceleration. Increase downforce sparingly to correct for understeer and oversteer tendencies, especially in powerful rear-wheel-driven vehicles that tend to break loose over sweeping high-speed turns.

Braking

Generally, you want braking to be even between the front and rear wheels. However, as you make changes via upgrades and other tuning, you may offset the balance of braking. If you find that the vehicle tends to understeer or oversteer under braking, you may have a braking imbalance.

You can correct for some amount of braking oversteer by moving the braking balance forward. Conversely, you can correct some understeer by moving the braking balance rearward. Too much braking balance to the rear, however, will upset stability under braking, while too much forward braking will contribute to understeer. Look for a neutral balance in the braking so that you feel neither understeer nor unsteady oversteer under hard braking conditions.